The present invention relates to resins preparable from aromatic compounds by condensation with aldehydes, and to their use for breaking water-oil emulsions, in particular in the production of crude oil.
During its recovery, crude oil is produced as an emulsion with water. Before the crude oil is further processed, these crude oil emulsions must be broken into the oil and water constituents. For this purpose, use is generally made of crude oil breakers. Crude oil breakers are surface-active compounds which are able to effect the required separation of the emulsion constituents within a short time.
Crude oil breakers include alkylphenol aldehyde resins, which are disclosed, for example, in U.S. Pat. No. 4,032,514. These resins are obtainable from the condensation of a p-alkylphenol with an aldehyde, in most cases formaldehyde. The resins are often used in alkoxylated form, as is disclosed, for example, in DE-A-24 45 873. For this, the free phenolic OH groups are reacted with an alkylene oxide.
However, alkylphenol aldehyde resins have recently become the subject of criticism because of their virtually unavoidable content of free alkylphenols and alkylphenol alkoxylates. According to the current state of knowledge, it cannot be ruled out that alkylphenols and alkylphenol alkoxylates have estrogenic action, which would be a potential threat to the animal kingdom.
The object was therefore to find new crude oil breakers which are at least comparable with the alkylphenol aldehyde resins in activity, but which do not comprise alkylphenols or alkylphenol alkoxylates, and are therefore not suspected of having estrogenic action.
Surprisingly, we have found that resins which can be prepared from N-substituted alkylaminobenzenes exhibit excellent action as crude oil breakers and are not suspected of having a hormone-like action.
The invention thus provides resins obtainable from compounds of the formula 1
in which the substituents R2 and HNR1 can be in the ortho, meta or para position relative to one another, and
R1 has the same meaning as R2, or has the meaning xe2x80x94COR2, where R1 is independent of R2,
R2 is C1-C30-alkyl, C2-C30-alkenyl, C6-C18-aryl, C7-C30-alkylaryl, by the steps, which can be carried out in any order, of
A) reaction with an aldehyde of the formula 2
R3xe2x80x94CHOxe2x80x83xe2x80x83(2),
wherein R3 is H, C1-C30-alkyl, C2-C30-alkenyl, C6-C18-aryl or C7-C30-alkylaryl, and
B) alkoxylation with a C2-C4-alkylene oxide in molar excess, such that the resulting alkoxylate has a degree of alkoxylation of from 1 to 100 alkylene oxide units per xe2x80x94NH group,
and the resin has a molecular weight of from 250 to 100,000 units.
The compounds of the formula (1) are essentially chemically homogeneous compounds which are not used in mixtures with one another. The term xe2x80x9cessentiallyxe2x80x9d means here that, for the preparation of the resins according to the invention, compounds of the formula (1) are used in commercially available purity. Proportions of other compounds covered by formula (1) can therefore be present in the resins, it being necessary, in particular, to draw attention to proportions of the two other aromatic substitution isomers in each case which have not been completely removed. The same is true for the aldehyde used for the condensation. This too is essentially to be used as a homogeneous substance, where aldehydes of commercially available purity are used.
R1 is preferably a xe2x80x94COR2 radical in which R2 is C1-C18-, in particular C2-C14-, especially C4-C12-alkyl or -alkenyl.
If one of the radicals R1, R2 or R3 is an alkenyl or alkyl radical, then its chain length is preferably from 2 to 24, particularly preferably from 4 to 22, especially from 4 to 18, carbon atoms. Alkyl and alkenyl radicals can either be linear or branched.
If one of the radicals R1, R2 or R3 is an alkylaryl radical, then alkylaryl is preferably a radical bonded via the aromatic ring, whose aromatic ring preferably includes 6 carbon atoms, and which carries, in the o-, m- or p-position relative to the abovementioned bond, an alkyl radical having a chain length of preferably from 1 to 18, particularly preferably from 4 to 16, in particular from 6 to 12, carbon atoms.
If step A is carried out first and then step B, the compounds of the formula 1 are then reacted with aldehydes of the formula 2 to give a resin. The aldehydes of the formula 2 are preferably those in which R8 is H or a C1-C6-alkyl radical, in particular H or a C1-C4-alkyl radical. In a particularly preferred embodiment, R8 is hydrogen. The condensation can either be acid-catalyzed or base-catalyzed. The resins resulting from the condensation are then alkoxylated with a C2-C4-alkylene oxide, preferably ethylene oxide or propylene oxide. The alkoxylating agent is used in molar excess. The alkoxylation takes place on the free NH groups of the resulting resin. Alkylene oxide is used in an amount such that the average degree of alkoxylation is between 1 and 100 alkylene oxide units per free NH group. The term xe2x80x9caverage degree of alkoxylationxe2x80x9d here means the average number of alkoxy units which are attached to each free NH group. It is preferably from 1 to 70, in particular from 2 to 50.
Steps A) (condensation) and B) (alkoxylation) are preferably carried out in this order. It is, however, also possible to carry them out in reverse order. In this case, the compounds of the formula 1 are firstly alkoxylated, and then converted into the resin.
The resin obtained after condensation and alkoxylation preferably has a molecular weight of from 500 to 50,000 units, in particular from 1000 to 10,000 units.
Preferred resins which are obtainable by the described process have the following structures: 
(AO)kNR1 is the alkoxylated NHR1 radical, in which AO is the alkylene oxide unit, and k is the degree of alkoxylation. The bridging of the aromatic rings via the carbon atom carrying the radical R3 can join onto any of the free positions of the aromatic rings. n is the degree of condensation of the resin. n is preferably a number from 2 to about 100, in particular from 3 to 50, particularly preferably from 4 to 30, especially from 4 to 10.
The invention further provides for the use of the resins according to the invention for breaking oil-water emulsions.
For use as crude oil breakers, the resins are added to the water-oil emulsions, which preferably takes place in solution. Preferred solvents are paraffinic or aromatic solvents. The amounts are from 0.0001 to 5% by weight, preferably from 0.0005 to 2% by weight, in particular from 0.0008 to 1 and especially from 0.001 to 0.1% by weight, of resin based on the oil content of the emulsion to be broken.
The compounds according to the invention are generally prepared by acid- or alkali-catalyzed condensation of the compounds of the formula 1 with the aldehydes of the formula 6, where the alkoxylation can precede or follow the condensation. The reaction temperature is generally between 50 and 170xc2x0 C., preferably from 120 to 165xc2x0 C. The reaction is normally carried out at atmospheric pressure. Examples of catalyzing acids which may be mentioned are HCl, H2SO4, sulfonic acids or H3PO4, and bases which may be mentioned are NaOH, KOH or triethylamine, which are used in amounts of from 0.1 to 50% by weight, based on the weight of the reaction mixture. The condensation generally requires from 30 min to 6 hours. The molar ratio between aldehyde and aromatic compound is generally from 0.5:1 to 4:1, preferably from 0.8:1 to 1.8:1.
The alkoxylation is carried out, as is known from the prior art, by reacting the resins with an alkylene oxide under an increased pressure of generally from 1.1 to 20 bar at temperatures of from 50 to 200xc2x0 C.